In a gas turbine, air pressurized in a compressor is mixed with a fuel in a combustor, generating a combustion gas which is a high-temperature fluid. The combustion gas is introduced into a combustion gas flow path of a turbine in which vanes and blades are alternately disposed. In the turbine, the blades and a rotor are rotated by the combustion gas that flows through the combustion gas flow path. As a result, the turbine converts the energy of the combustion gas into rotational energy, and applies a rotational driving force to the compressor and a power generator.
The combustion gas flow path through which the combustion gas flows is surrounded by a wall portion on an inner peripheral side and an outer peripheral side, and forms a ring shape. The wall portion of the combustion gas flow path is formed by arranging planar hot parts in a circumferential direction and an axial direction. Specifically, on the inner peripheral side of the combustion gas flow path, inner shrouds attached to vane base ends are arranged in the circumferential direction in a ring shape. In addition, on the inner peripheral side of the combustion gas flow path, platforms attached to blade base ends are arranged in the circumferential direction in a ring shape, in a position adjacent to the inner shrouds in the axial direction along the combustion gas flow path. Accordingly, ring-shaped bodies of the inner shrouds and the platforms are alternately arranged in the axial direction of the rotor, and constitute the wall portion on the inner peripheral side. On the outer peripheral side of the combustion gas flow path, outer shrouds attached to vane leading ends are arranged in the circumferential direction in a ring shape. In addition, on the outer peripheral side of the combustion gas flow path, ring segments curved in an arc shape are arranged in the circumferential direction in a ring shape, in a position adjacent to the outer shrouds in the axial direction along the combustion gas flow path. Accordingly, the ring-shaped bodies of the outer shrouds and the ring segments are alternately arranged in the axial direction, and constitute the wall portion on the outer peripheral side.
The hot parts that constitute such a combustion gas flow path and come into contact with the high-temperature combustion gas are cooled utilizing a portion of the compressed air as cooling air. Examples of a structure for cooling the hot parts of the gas turbine include a cooling structure disclosed in Patent Literature 1. In this cooling structure, a cooling air flow path that extends in the axial direction is formed in an end surface of a shroud of a vane. Specifically, a channel that extends in the axial direction is formed in the end surface of the shroud of the vane. An opening of this channel is blocked by a plug, thereby forming the cooling air flow path that extends in the axial direction.